Quiet Stone Treaty

Every dwarf knows of the war seven thousand years ago when one House fell to madness, and was sealed away below the surface. Stories abound of the grisly conflict leading up to that final battle and the 'House' of dwarves who forake their family names to forever hunt the surface in search of signs that the betrayers will return. Less well known to dwarves is the treaty that preceded the conflict by mere decades, and lent the stories of the war their horrific flair. The Quiet Stone Treaty was signed by leaders of every great House among the dwarves and the heads of every minor family, before being consecrated by priests and delivered to the gods for enforcing. In the three thousand years since the first dwarves made the twenty-five families, dwarven magic and engineering had reached incredible heights, and incredible destructive potential. Their empires blanketed the earth and the dwarves had devised weapons that could level whole cities and flatten mountains- which they used. Though humans bore the brunt of these attacks, the dwarves turned these weapons on each other as well, until Kytheria herself intervened. Massive earthquakes rocked the greatest dwarven settlements (which had been built far from fault lines), and storms scoured the land of dwarven settlements with a ferocity never before seen in nature. Dreams and visions sent to dwarven priests made it clear that the world herself would not tolerate the use of these weapons any longer, and the dwarves came together and agreed to ban their use and creation.
This is the reason that the betrayers were able to challenge the collective might of twenty-four other Houses, for they never stopped making these horrific weapons, and had found dark and twisted entities to worship who shielded them from Kytheria's wrath. The entire dwarven nation united to defeat them and drive them below into the bowels of the world, where they must contend with Kytheria's simmering anger even as their bizarre gifts allow them to eke out an existence in the dark, plotting revenge. The Quiet Stone Treaty binds every dwarven leader against making weapons so destructive, and a ny who try receive warning visions and dreams, and will eventually be targeted by a religious order if they don't cease. The world has become a considerably safer place as a result, and even if dwarven empires haven't reached the heights of those early days, the peace to be had with their own mother world is worth it.